2004 Archives

Transit of Venus,
June 8, 2004

View archives of programs webcast live from the National Observatory of Athens–Penteli Station.
The first program watches Venus enter the disk of the sun, and the second sees Venus leave the sun several hours later. During both programs, a
stronomers describe the fascinating history of earlier transits, what we've learned from them, and how transits across faraway stars are helping us identify and learn about planets outside of our solar system.

There are two sets of images here. One set was taken through a
special filter that lets through only the red light given off
by hydrogen gas (called "hydrogen-alpha"). This lets you see details
on the Sun's surface invisible in the other white-light photos.
The optical filtering system causes the images of the hydrogen-alpha
photos to be flipped relative to the white light images.

The names
of the images tell you the date and time the image was taken.
For instance, a file named 2004-06-08T05-13-53.774.jpg was taken
on June 8th, 2004 at 5:13:53.774 Universal
Time. You will note that in some images the Sun becomes partially
obscured with clouds. Images where the sun is completely obscured
(black frames) have been discarded. This results in the time sequence
of photos seemingly skipping. No good images have been left out!

The images were taken with two SBIG ST-10XE CCD Cameras, one on each telescope. The white-light telescope
was a Vixen
ED102SS (102mm diameter, focal length 660mm, f/6.5) with a Baader filter. The H-alpha telescope was a Coronado Maxscope 70 double-stacked (60mm diameter, focal length 400mm,
f/6.67, bandwidth < 0.5A) with a Coronado CEMAX 2x barlow. Both telescopes were mounted on the same equatorial
telescope drive (Losmandy GM8 on a G11 tripod with Gemini controller system). The photographer,
Igor Rudermam of U. C.
Berkeley's Space Sciences Laboratory, sits behind the telescope.